Carol Thatcher, 59, paid tribute to her mother for developing skills gleaned from her “austere childhood” and a lack of "luxuries", which helped shape her glittering career in public life.

Lady Thatcher’s daughter said skills such as discipline, motivation and “tunnel vision” were instrumental in her political career, which ended in her becoming the country’s first and only female occupant of Downing Street.

Miss Thatcher said that her mother’s tough upbringing helped her become a “very motivated” person.

The pre-recorded comments were made in a BBC documentary last night, which was presented by Andrew Marr, one of the corporation's leading political journalists.

She told the former BBC Political Editor: “My mother certainly had an austere childhood. Material luxuries were in short supply.

“I think everything she put into use in her career in later life, was gleaned from her childhood – the discipline, the motivation and the tunnel vision.

“She was a very motivated child, a very motivated teenager and we all know what a motivated adult she became.”

Carol Thatcher moved to Switzerland

Mrs Thatcher and her twin brother Sir Mark, are currently abroad and will not be returning to Britain in the "immediate future", Lord Bell said yesterday.

Sir Mark and Carol Thatcher have asked to grieve in private and will not be making a statement. Sir Mark and his wife are understood to live in Marbella, Spain, while his twin sister Carol has a home in Switzerland.

Lord Bell said they would not return to Britain straightaway but would be back for the funeral.

Carol Thatcher moved to the European country after becoming increasingly disenchanted with life in Britain. In 2009 she was dropped by the BBC after using the word "golliwog" to describe a tennis player on the One show.

She subsequently told The Daily Telegraph that she was considering life abroad. "I'm becoming increasingly despondent about the state of this country, and I am beginning to look elsewhere."

She has a flat in Klosters, where she had an on-off relationship with Marco Grass, a ski instructor.

Sir Mark Thatcher is escorted by police from the Scorpions branch after his arrest at his house in Cape Town in 2004

Sir Mark is thought to have lived in Spain for about five years, but visited his mother on a regular basis and took her for lunch on her 87th birthday. In 2004 he was arrested in South Africa for his alleged involvement in a failed coup in Equatorial Guinea.

He denied plotting or knowingly financing the coup, but admitted chartering an aircraft allegedly intended to fly an exiled opposition leader into the county.

He is now thought to be involved in a property development business.

Neither of Baroness Thatcher’s children have said anything further since their mother’s death.